68 PRACTICAL ORGANIC CHEMISTRY caustic potash on the water-bath, and then distilling. It is freed from water by standing for twenty-four hours in a flask one-third filled with freshly-burnt quicklime, and re-distilling from the water-bath, using a thermometer. Properties. — Colourless liquid ; b. p. 66—67°'; sp. gr. 0796 at 20°. PREPARATION 6. Methyl Iodide (lodomethane), CH3I Dumas and Peligot, Annalen, 1835, 15, 20. 1 8 grins, methyl alcohol. 5 „ red phosphorus 50 „ iodine Attach a flask (250 c.c.) to an upright condenser, and bring into it the methyl alcohol and red phosphorus. Add the iodine gradually by detaching the flask for a moment from the con- denser. A considerable evolution of heat occurs. When the iodine has'been added the flask is left attached to the condenser over night, and the contents then distilled from the water-bath using a similar apparatus to that of Fig\ 43, p. 53. The dis- tillate is shaken up with dilute caustic soda in a separating funnel, to remove iodine and hydriodic acid. If sufficient caustic soda has been used the lower layer of methyl iodide will be colourless. Separate -the methyl iodide, add a few. pieces of solid calcium chloride, and after standing until clear, distil from . the water-bath with thermometer. Yield 45 grams. Ethyl iodide and the other alkyl iodides are prepared in precisely the same fashion. Properties. — Colourless, highly refractive liquid ; b. p. 45° ; sp:gr. 2-27 at 15°. Reaction. — Shake a few drops of methyl iodide with an alcoholic solution of silver nitrate. A white precipitate of a compound of silver iodide and silver nitrate is deposited, which is decomposed and gives yellow silver iodide on adding water. See Appendix^ p. 240.